Apparatus for taking photographs with röntgen rays.



F. DESSAU'ER. APPARATUS FOR TAKING PHOTOGRAPHS WITH RUNTGEN RAYS.

APPLICATION IILED NOV. 8, 1909.

1,096,691, Patented May 12, 1914,

QV/i Unwam Qmvew v 1 7 UNITED STATES PATENT OFFICE.

FRIEDRICH DESSAUER, OF ASCHAFFENBURG, GERMANY.

. APPARATUS FOR TAKING PHOTOGRAPHS WITH RGNTGEN RAYS.

Specification of Letters Patent.

Patented May 12,1914.

Application filed November 8, 1909. Serial N 0. 526,795.

and has particular reference to an improvement in means for exposm photographic plates used in connection with Xray photography.

The 0 ject in view in this connection is to construct an X-ray photogra hing apparatus which is capabe of e ecting an extremely rapid exposure of the photographic plate as well as to simplify the structure of,

such a mechanism.

With this object in view, my invention will hereinafter be fully set forth and described, reference bein had to the accompanying drawing, in w ich one embodiment of my invention is shown.

For some time efforts have been made to shorten the length of time required for taking X-ray pictures, so as to render it possible to take a truly instantaneous picture. In some cases, so-called instantaneous pictures, were taken in from one to ten sec onds, and exposures of as much as twenty seconds have been considered as instantaneous. In a few isolated cases pictures have been takenin less than one second, ran ing in time from one quarter to one twentyfth of a second. Even the latter cases, however, do not really come under the head of instantaneous exposures, and one can only call an exposure instantaneous when the period of light, with reference to the rapidity of the movement of the object to be photographed, such, for instance, as the beating heart, or voluntar or involuntary movements of the muse es, is of short duration. Thus, a practical instantaneous exposure is one which is made in, at the most, one fiftieth of a second, and generally ranges from one hundredth to one three-hundredth part of a second. In radiograms taken with the apparatus described herein the outlines of the beating heart show absolutely sharp on the plate.

So-called instantaneous pictures taken by the old methods, and the times of exposure of which range from one to twenty seconds, have almost invariably been secured by apparatuses in which were used a direct current powerful induction coil and Wehnelt interrupter or less frequently, a mercury interrupter, the secondary high tension alternating current being transformed into high tension continuous current. a

The present invention, by which pictures of 1/100 to 1/300 second exposures have been made, is based on the single excitement of the secondary coil of'a transformer by the interruption of the primary continuous current, and a high tension transformer is used for that purpose, said transformer being constructed similar to a simple induction coil. Furthermore, it uses a continuous current, but, in contradistinction to other apparatuses, no continuously operating make and break is employed. The use of an interrupter makes an instantaneous exposure impossible, and instantaneous photographs are successful with the herein described apparatus, chiefly, because a sin le impulse of discharge is used, the duration of which, with the high potential transformer lies between 1/50 and 1/300 of a second.

In the accompanying drawings, which represent one form of the invention, a is the direct current transformer, and has one pole of the primary coil connected to one side of a current source 8. A condenser b might be connected with one ole in contact with the other terminal of t e primary coil of the transformer a, and is furnished of suitable size so that when the primary circuit is broken, the strength of the discharge of current can be raised by'the diversion of the current to said condenser and thence back over the line, producing on the secondary coil an induced current of a very high voltage capable of ionizing the X-ray tube.

In the circuit established between the primary coil of the transformer a, the current source 8 and the condenser b is a switch a. Said switch is, or may be, of any type and may consist of a switch arm a and a leaf which may enter the fixed contact members; the latter being connected to the condenser terminal. Also connected in parallel with said condenser and the transformer a is a fuse d which is constructed and tested so that its fu'sin and load curve are accurately known quantities. The fuse is made of suitable length and is embedded in gypsum or some similar substance, those substances being especially suitable which can be pulverized suddenly. v Inorder to promote the breakage and the instantaneous extinction of the spark induced by the sudden burning 'out, other materials may be added to the exactly at the moment, 2'. e. not earlier nor later, when the magnetizing current has attained that maximum strength which is nec essary in order to obtain the desired effect. The fuse thus insures that on the one hand the current strength required is not exceeded, and on the other hand the circuit is not interrupted before the current has attained its critical height. The thickness of the fuse is adapted tothe desired effect.

\Vhen the switch 0 is closed, the current in the primary circuit becomes quickly and continuously stronger in overwhelming the inductive reactance in the transformer (1, until the fuse is consumed. As above stated, the fusing and load curves of the fuse are accurately determined quantities, so that the interval between the closing of the switch 0 and the burning out of the fuse will be absolutely known. The consumption of the fuse must be effected as quickly as possible, and for this reason, thefuse is made-of suitable length and is incased in impermeable material. In this way, a very high breaking velocity during the interruption will be in sured and the primary breaking contact self induction spark be rapidly extinguished and the secondary breaking contact induction attain an exceedingly high potential. For each exposure, a new fuse is inserted in the circuit. Thus, it is obvious that the solution of the problem of instantaneous X-ray photography, as contemplated in this invention, depends on the possibility of a momentary large current, under the proteotion of the circuit current against exces slvc overloadlng, and the principal feature of this invention lies in this, that after the switching on of the current, a forceful switching off is caused after a time which is equal to the necessary duration'of the magnetizing current, and which allows a'high overloading without danger.

As already stated, it is possible to overload electric machines fora very short interval of time to the extent of a few hundred per cent, and by this apparatus, the overloading is carried out without danger to the machine, by the almost simultaneous opening of the circuit. The discharge current strength can be raised by the passage of a current of a sufiiciently high strength through the transformer so that any desired X-ray exposure can be taken by'a single discharge impulse.

What I claim is 1. In an apparatus for taking instant-aneous X-ray photographs, the combination of a direct current transformer having an X- ray tube connected to its secondary coil, a

switch, a current source adapted to overload the primary circuit when said switch is closed, and means for automatically breaking the primary circuit when the latter is overloaded to create a single intense excitement of the secondary coil circuit.

2. In an apparatus and method for taking instantaneous X-ray photographs, the combination of a direct current transformer having an X-ray tube in circuit with the secondary thereof, a current source, a swltch in the primary circuit and a fuse in the circuit adapted to be destroyed when said switch is closed, whereby the primary circuit is momentarily overloaded to induce a 

